Added PointSprites Support for renderers that do not support Geometry Shaders

Change-Id: Iae9ac5f8fbba68dba5e49ccda7bb7eebb05c8e9a
Reviewed-on: https://chromium-review.googlesource.com/240450
Reviewed-by: Geoff Lang <geofflang@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Tested-by: Geoff Lang <geofflang@chromium.org>
diff --git a/tests/angle_tests/PointSpritesTest.cpp b/tests/angle_tests/PointSpritesTest.cpp
new file mode 100644
index 0000000..d109893
--- /dev/null
+++ b/tests/angle_tests/PointSpritesTest.cpp
@@ -0,0 +1,390 @@
+#include "ANGLETest.h"
+
+// Use this to select which configurations (e.g. which renderer, which GLES
+// major version) these tests should be run against.
+//
+// Some of the pointsprite tests below were ported from Khronos WebGL
+// conformance test suite.
+
+//
+// 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_TYPED_TEST_CASE(PointSpritesTest, ES2_D3D9, ES2_D3D11, ES2_D3D11_FL9_3);
+
+template<typename T>
+class PointSpritesTest : public ANGLETest
+{
+  protected:
+    const int windowWidth = 256;
+    const int windowHeight = 256;
+    PointSpritesTest() : ANGLETest(T::GetGlesMajorVersion(), T::GetPlatform())
+    {
+        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
+TYPED_TEST(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;
+    GLfloat step = floorf(maxPointSize / 4);
+    GLfloat pointStep = std::max<GLfloat>(1.0f, 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[] = { -0.5 + pixelOffset, -0.5 + pixelOffset,
+                             0.5 + pixelOffset, -0.5 + pixelOffset,
+                            -0.5 + pixelOffset,  0.5 + pixelOffset,
+                             0.5 + pixelOffset,  0.5 + 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 = -0.5 + px + pixelOffset;
+            float pointY = -0.5 + 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;
+                    float xf = floorf(s2p(pointX + u * pointWidth));
+                    float yf = floorf(s2p(pointY + v * pointWidth));
+                    float s = 0.5 + (xf + 0.5 - xw) / maxPointSize;
+                    float t = 0.5 + (yf + 0.5 - yw) / maxPointSize;
+                    GLubyte color[4] = { floorf(s * 255), 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
+TYPED_TEST(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
+TYPED_TEST(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
+TYPED_TEST(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);
+        }
+    );
+
+    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, _countof(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 = 178; y < 180; ++y)
+    {
+        for (GLint x = 178; x < 180; ++x)
+        {
+            // 179x179 is expected to be a red pixel
+            // All others are black
+            GLubyte expectedColor[4] = { 0, 0, 0, 0 };
+            if (x == 179 && y == 179)
+            {
+                expectedColor[0] = 255;
+                expectedColor[3] = 255;
+            }
+            EXPECT_PIXEL_EQ(x, y, expectedColor[0], expectedColor[1], expectedColor[2], expectedColor[3]);
+        }
+    }
+
+    swapBuffers();
+
+    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, _countof(vertices) / 3);
+        ASSERT_GL_NO_ERROR();
+
+        // Test the pixels to ensure the target is ALL Red pixels
+        for (GLint y = 178; y < 180; ++y)
+        {
+            for (GLint x = 178; x < 180; ++x)
+            {
+                EXPECT_PIXEL_EQ(x, y, 255, 0, 0, 255);
+            }
+        }
+    }
+
+    glDeleteBuffers(1, &vertexObject);
+}