src/tests/gl_tests/PointSpritesTest.cpp

//
// Copyright 2015 The ANGLE Project Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
//
// Some of the pointsprite tests below were ported from Khronos WebGL
// conformance test suite.

#include "test_utils/ANGLETest.h"

#include <cmath>

using namespace angle;

class PointSpritesTest : public ANGLETest
{
  protected:
    const int windowWidth = 256;
    const int windowHeight = 256;
    PointSpritesTest()
    {
        setWindowWidth(windowWidth);
        setWindowHeight(windowHeight);
        setConfigRedBits(8);
        setConfigGreenBits(8);
        setConfigBlueBits(8);
        setConfigAlphaBits(8);
    }

    virtual void SetUp()
    {
        ANGLETest::SetUp();
    }

    float s2p(float s)
    {
        return (s + 1.0f) * 0.5f * (GLfloat)windowWidth;
    }
};

// Checks gl_PointCoord and gl_PointSize
// https://www.khronos.org/registry/webgl/sdk/tests/conformance/glsl/variables/gl-pointcoord.html
TEST_P(PointSpritesTest, PointCoordAndPointSizeCompliance)
{
    const std::string fs = SHADER_SOURCE
    (
        precision mediump float;
        void main()
        {
            gl_FragColor = vec4(
                gl_PointCoord.x,
                gl_PointCoord.y,
                0,
                1);
        }
    );

    const std::string vs = SHADER_SOURCE
    (
        attribute vec4 vPosition;
        uniform float uPointSize;
        void main()
        {
            gl_PointSize = uPointSize;
            gl_Position = vPosition;
        }
    );

    GLuint program = CompileProgram(vs, fs);
    ASSERT_NE(program, 0u);
    ASSERT_GL_NO_ERROR();

    glUseProgram(program);

    GLfloat pointSizeRange[2] = {};
    glGetFloatv(GL_ALIASED_POINT_SIZE_RANGE, pointSizeRange);

    GLfloat maxPointSize = pointSizeRange[1];

    ASSERT_TRUE(maxPointSize >= 1);
    maxPointSize = floorf(maxPointSize);
    ASSERT_TRUE((int)maxPointSize % 1 == 0);

    maxPointSize = std::min(maxPointSize, 64.0f);
    GLfloat pointWidth = maxPointSize / windowWidth;
    GLint step = static_cast<GLint>(floorf(maxPointSize / 4));
    GLint pointStep = std::max<GLint>(1, step);

    GLint pointSizeLoc = glGetUniformLocation(program, "uPointSize");
    ASSERT_GL_NO_ERROR();

    glUniform1f(pointSizeLoc, maxPointSize);
    ASSERT_GL_NO_ERROR();

    GLfloat pixelOffset = ((int)maxPointSize % 2) ? (1.0f / (GLfloat)windowWidth) : 0;
    GLuint vertexObject = 0;
    glGenBuffers(1, &vertexObject);
    ASSERT_NE(vertexObject, 0U);
    ASSERT_GL_NO_ERROR();

    glBindBuffer(GL_ARRAY_BUFFER, vertexObject);
    ASSERT_GL_NO_ERROR();

    GLfloat thePoints[] = { -0.5f + pixelOffset, -0.5f + pixelOffset,
                             0.5f + pixelOffset, -0.5f + pixelOffset,
                            -0.5f + pixelOffset,  0.5f + pixelOffset,
                             0.5f + pixelOffset,  0.5f + pixelOffset };

    glBufferData(GL_ARRAY_BUFFER, sizeof(thePoints), thePoints, GL_STATIC_DRAW);
    ASSERT_GL_NO_ERROR();

    glEnableVertexAttribArray(0);
    glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, 0, 0);

    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

    glDrawArrays(GL_POINTS, 0, 4);
    ASSERT_GL_NO_ERROR();

    glDeleteBuffers(1, &vertexObject);

    std::string debugText;
    for (float py = 0; py < 2; ++py) {
        for (float px = 0; px < 2; ++px) {
            float pointX = -0.5f + px + pixelOffset;
            float pointY = -0.5f + py + pixelOffset;
            for (int yy = 0; yy < maxPointSize; yy += pointStep) {
                for (int xx = 0; xx < maxPointSize; xx += pointStep) {
                    // formula for s and t from OpenGL ES 2.0 spec section 3.3
                    float xw = s2p(pointX);
                    float yw = s2p(pointY);
                    float u = xx / maxPointSize * 2 - 1;
                    float v = yy / maxPointSize * 2 - 1;
                    int xf = static_cast<int>(floorf(s2p(pointX + u * pointWidth)));
                    int yf = static_cast<int>(floorf(s2p(pointY + v * pointWidth)));
                    float s = 0.5f + (xf + 0.5f - xw) / maxPointSize;
                    float t = 0.5f + (yf + 0.5f - yw) / maxPointSize;
                    GLubyte color[4] = { static_cast<GLubyte>(floorf(s * 255)), static_cast<GLubyte>(floorf((1 - t) * 255)), 0, 255 };
                    EXPECT_PIXEL_NEAR(xf, yf, color[0], color[1], color[2], color[3], 4);
                }
            }
        }
    }
}

// Verify that drawing a point without enabling any attributes succeeds
// https://www.khronos.org/registry/webgl/sdk/tests/conformance/rendering/point-no-attributes.html
TEST_P(PointSpritesTest, PointWithoutAttributesCompliance)
{
    const std::string fs = SHADER_SOURCE
    (
        precision mediump float;
        void main()
        {
            gl_FragColor = vec4(0.0, 1.0, 0.0, 1.0);
        }
    );

    const std::string vs = SHADER_SOURCE
    (
        void main()
        {
            gl_PointSize = 1.0;
            gl_Position = vec4(0.0, 0.0, 0.0, 1.0);
        }
    );

    GLuint program = CompileProgram(vs, fs);
    ASSERT_NE(program, 0u);
    ASSERT_GL_NO_ERROR();

    glUseProgram(program);

    glDrawArrays(GL_POINTS, 0, 1);
    ASSERT_GL_NO_ERROR();

    // expect the center pixel to be green
    EXPECT_PIXEL_EQ((windowWidth - 1) / 2, (windowHeight - 1) / 2, 0, 255, 0, 255);
}

// This is a regression test for a graphics driver bug affecting end caps on roads in MapsGL
// https://www.khronos.org/registry/webgl/sdk/tests/conformance/rendering/point-with-gl-pointcoord-in-fragment-shader.html
TEST_P(PointSpritesTest, PointCoordRegressionTest)
{
    const std::string fs = SHADER_SOURCE
    (
        precision mediump float;
        varying vec4 v_color;
        void main()
        {
            // It seems as long as this mathematical expression references
            // gl_PointCoord, the fragment's color is incorrect.
            vec2 diff = gl_PointCoord - vec2(.5, .5);
            if (length(diff) > 0.5)
                discard;

            // The point should be a solid color.
            gl_FragColor = v_color;
        }
    );

    const std::string vs = SHADER_SOURCE
    (
        varying vec4 v_color;
        // The X and Y coordinates of the center of the point.
        attribute vec2 a_vertex;
        uniform float u_pointSize;
        void main()
        {
            gl_PointSize = u_pointSize;
            gl_Position = vec4(a_vertex, 0.0, 1.0);
            // The color of the point.
            v_color = vec4(0.0, 1.0, 0.0, 1.0);
        }
    );

    GLuint program = CompileProgram(vs, fs);
    ASSERT_NE(program, 0u);
    ASSERT_GL_NO_ERROR();

    glUseProgram(program);

    GLfloat pointSizeRange[2] = {};
    glGetFloatv(GL_ALIASED_POINT_SIZE_RANGE, pointSizeRange);

    GLfloat maxPointSize = pointSizeRange[1];

    ASSERT_TRUE(maxPointSize > 2);

    glClearColor(0, 0, 0, 1);
    glDisable(GL_DEPTH_TEST);
    glClear(GL_COLOR_BUFFER_BIT);

    GLint pointSizeLoc = glGetUniformLocation(program, "u_pointSize");
    ASSERT_GL_NO_ERROR();

    GLfloat pointSize = std::min<GLfloat>(20.0f, maxPointSize);
    glUniform1f(pointSizeLoc, pointSize);
    ASSERT_GL_NO_ERROR();

    GLuint vertexObject = 0;
    glGenBuffers(1, &vertexObject);
    ASSERT_NE(vertexObject, 0U);
    ASSERT_GL_NO_ERROR();

    glBindBuffer(GL_ARRAY_BUFFER, vertexObject);
    ASSERT_GL_NO_ERROR();

    GLfloat thePoints[] = { 0.0f, 0.0f };

    glBufferData(GL_ARRAY_BUFFER, sizeof(thePoints), thePoints, GL_STATIC_DRAW);
    ASSERT_GL_NO_ERROR();

    glEnableVertexAttribArray(0);
    glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, 0, 0);

    glDrawArrays(GL_POINTS, 0, 1);
    ASSERT_GL_NO_ERROR();

    // expect the center pixel to be green
    EXPECT_PIXEL_EQ((windowWidth - 1) / 2, (windowHeight - 1) / 2, 0, 255, 0, 255);

    glDeleteBuffers(1, &vertexObject);
}

// Verify GL_VERTEX_PROGRAM_POINT_SIZE is enabled
// https://www.khronos.org/registry/webgl/sdk/tests/conformance/rendering/point-size.html
TEST_P(PointSpritesTest, PointSizeEnabledCompliance)
{
    const std::string fs = SHADER_SOURCE
    (
        precision mediump float;
        varying vec4 color;

        void main()
        {
            gl_FragColor = color;
        }
    );

    const std::string vs = SHADER_SOURCE
    (
        attribute vec3 pos;
        attribute vec4 colorIn;
        uniform float pointSize;
        varying vec4 color;

        void main()
        {
            gl_PointSize = pointSize;
            color = colorIn;
            gl_Position = vec4(pos, 1.0);
        }
    );

    // The WebGL test is drawn on a 2x2 canvas. Emulate this by setting a 2x2 viewport.
    glViewport(0, 0, 2, 2);

    GLuint program = CompileProgram(vs, fs);
    ASSERT_NE(program, 0u);
    ASSERT_GL_NO_ERROR();

    glUseProgram(program);

    glDisable(GL_BLEND);

    // The choice of (0.4, 0.4) ensures that the centers of the surrounding
    // pixels are not contained within the point when it is of size 1, but
    // that they definitely are when it is of size 2.
    GLfloat vertices[] = { 0.4f, 0.4f, 0.0f };
    GLubyte colors[] = { 255, 0, 0, 255 };

    GLuint vertexObject = 0;
    glGenBuffers(1, &vertexObject);
    ASSERT_NE(vertexObject, 0U);
    ASSERT_GL_NO_ERROR();

    glBindBuffer(GL_ARRAY_BUFFER, vertexObject);
    ASSERT_GL_NO_ERROR();

    glBufferData(GL_ARRAY_BUFFER, sizeof(vertices) + sizeof(colors), NULL, GL_STATIC_DRAW);
    ASSERT_GL_NO_ERROR();

    glBufferSubData(GL_ARRAY_BUFFER, 0, sizeof(vertices), vertices);
    ASSERT_GL_NO_ERROR();

    glBufferSubData(GL_ARRAY_BUFFER, sizeof(vertices), sizeof(colors), colors);
    ASSERT_GL_NO_ERROR();

    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 0, 0);
    glEnableVertexAttribArray(0);

    glVertexAttribPointer(1, 4, GL_UNSIGNED_BYTE, GL_TRUE, 0, (GLvoid*)sizeof(vertices));
    glEnableVertexAttribArray(1);

    GLint pointSizeLoc = glGetUniformLocation(program, "pointSize");
    ASSERT_GL_NO_ERROR();

    glUniform1f(pointSizeLoc, 1.0f);
    ASSERT_GL_NO_ERROR();

    glDrawArrays(GL_POINTS, 0, static_cast<GLsizei>(ArraySize(vertices)) / 3);
    ASSERT_GL_NO_ERROR();

    // Test the pixels around the target Red pixel to ensure
    // they are the expected color values
    for (GLint y = 0; y < 2; ++y)
    {
        for (GLint x = 0; x < 2; ++x)
        {
            // 1x1 is expected to be a red pixel
            // All others are black
            GLubyte expectedColor[4] = { 0, 0, 0, 0 };
            if (x == 1 && y == 1)
            {
                expectedColor[0] = 255;
                expectedColor[3] = 255;
            }
            EXPECT_PIXEL_EQ(x, y, expectedColor[0], expectedColor[1], expectedColor[2], expectedColor[3]);
        }
    }

    GLfloat pointSizeRange[2] = {};
    glGetFloatv(GL_ALIASED_POINT_SIZE_RANGE, pointSizeRange);

    if (pointSizeRange[1] >= 2.0)
    {
        // Draw a point of size 2 and verify it fills the appropriate region.
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

        glUniform1f(pointSizeLoc, 2.0f);
        ASSERT_GL_NO_ERROR();

        glDrawArrays(GL_POINTS, 0, static_cast<GLsizei>(ArraySize(vertices)) / 3);
        ASSERT_GL_NO_ERROR();

        // Test the pixels to ensure the target is ALL Red pixels
        for (GLint y = 0; y < 2; ++y)
        {
            for (GLint x = 0; x < 2; ++x)
            {
                EXPECT_PIXEL_EQ(x, y, 255, 0, 0, 255);
            }
        }
    }

    glDeleteBuffers(1, &vertexObject);
}

// Verify that rendering works correctly when gl_PointSize is declared in a shader but isn't used
TEST_P(PointSpritesTest, PointSizeDeclaredButUnused)
{
    const std::string vs = SHADER_SOURCE
    (
        attribute highp vec4 position;

        void main(void)
        {
            gl_PointSize = 1.0;
            gl_Position = position;
        }
    );

    const std::string fs = SHADER_SOURCE
    (
        void main(void)
        {
            gl_FragColor = vec4(1.0, 0.0, 0.0, 1.0);
        }
    );

    GLuint program = CompileProgram(vs, fs);
    ASSERT_NE(program, 0u);
    ASSERT_GL_NO_ERROR();

    glUseProgram(program);
    drawQuad(program, "position", 0.5f, 1.0f);
    ASSERT_GL_NO_ERROR();

    // expect the center pixel to be red
    EXPECT_PIXEL_EQ(getWindowWidth() / 2, getWindowHeight() / 2, 255, 0, 0, 255);

    glDeleteProgram(program);
}

// Use this to select which configurations (e.g. which renderer, which GLES
// major version) these tests should be run against.
//
// We test on D3D11 9_3 because the existing D3D11 PointSprite implementation
// uses Geometry Shaders which are not supported for 9_3.
// D3D9 and D3D11 are also tested to ensure no regressions.
ANGLE_INSTANTIATE_TEST(PointSpritesTest, ES2_D3D9(), ES2_D3D11(), ES2_D3D11_FL9_3());