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Offload vertex transformation to the GPU

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This commit is contained in:
Clownacy 2020-09-15 16:03:55 +01:00
parent 07e4e3b971
commit 0f5af36951
1 changed files with 42 additions and 10 deletions
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52
src/Backends/Rendering/OpenGL3.cpp
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@ -66,6 +66,7 @@ static struct
struct
{
GLint texture_coordinate_transform;
GLint vertex_transform;
} uniforms;
} program_texture;
@ -75,6 +76,7 @@ static struct
struct
{
GLint texture_coordinate_transform;
GLint vertex_transform;
} uniforms;
} program_texture_colour_key;
@ -93,6 +95,7 @@ static struct
struct
{
GLint texture_coordinate_transform;
GLint vertex_transform;
GLint colour;
} uniforms;
} program_glyph;
@ -131,6 +134,7 @@ void main() \
static const GLchar *vertex_shader_texture = " \
#version 100\n \
uniform mat4 vertex_transform; \
uniform vec2 texture_coordinate_transform; \
attribute vec2 input_vertex_coordinates; \
attribute vec2 input_texture_coordinates; \
@ -138,7 +142,7 @@ varying vec2 texture_coordinates; \
void main() \
{ \
texture_coordinates = input_texture_coordinates * texture_coordinate_transform; \
gl_Position = vec4(input_vertex_coordinates.xy, 0.0, 1.0); \
gl_Position = vec4(input_vertex_coordinates.xy, 0.0, 1.0) * vertex_transform; \
} \
";
@ -202,6 +206,7 @@ void main() \
static const GLchar *vertex_shader_texture = " \
#version 150 core\n \
uniform mat4 vertex_transform; \
uniform vec2 texture_coordinate_transform; \
in vec2 input_vertex_coordinates; \
in vec2 input_texture_coordinates; \
@ -209,7 +214,7 @@ out vec2 texture_coordinates; \
void main() \
{ \
texture_coordinates = input_texture_coordinates * texture_coordinate_transform; \
gl_Position = vec4(input_vertex_coordinates.xy, 0.0, 1.0); \
gl_Position = vec4(input_vertex_coordinates.xy, 0.0, 1.0) * vertex_transform; \
} \
";
@ -504,12 +509,15 @@ RenderBackend_Surface* RenderBackend_Init(const char *window_title, size_t scree
{
// Get shader uniforms
program_texture.uniforms.texture_coordinate_transform = glGetUniformLocation(program_texture.id, "texture_coordinate_transform");
program_texture.uniforms.vertex_transform = glGetUniformLocation(program_texture.id, "vertex_transform");
program_texture_colour_key.uniforms.texture_coordinate_transform = glGetUniformLocation(program_texture_colour_key.id, "texture_coordinate_transform");
program_texture_colour_key.uniforms.vertex_transform = glGetUniformLocation(program_texture_colour_key.id, "vertex_transform");
program_colour_fill.uniforms.colour = glGetUniformLocation(program_colour_fill.id, "colour");
program_glyph.uniforms.texture_coordinate_transform = glGetUniformLocation(program_glyph.id, "texture_coordinate_transform");
program_glyph.uniforms.vertex_transform = glGetUniformLocation(program_glyph.id, "vertex_transform");
program_glyph.uniforms.colour = glGetUniformLocation(program_glyph.id, "colour");
// Set up framebuffer (used for surface-to-surface blitting)
@ -587,8 +595,16 @@ void RenderBackend_DrawScreen(void)
last_source_texture = 0;
last_destination_texture = 0;
const GLfloat vertex_transform[4 * 4] = {
1.0f, 0.0f, 0.0f, 0.0f,
0.0f, 1.0f, 0.0f, 0.0f,
0.0f, 0.0f, 1.0f, 0.0f,
0.0f, 0.0f, 0.0f, 1.0f,
};
glUseProgram(program_texture.id);
glUniform2f(program_texture.uniforms.texture_coordinate_transform, 1.0f, 1.0f);
glUniformMatrix4fv(program_texture.uniforms.vertex_transform, 1, GL_FALSE, vertex_transform);
glDisable(GL_BLEND);
@ -771,9 +787,17 @@ void RenderBackend_Blit(RenderBackend_Surface *source_surface, const RenderBacke
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, destination_surface->texture_id, 0);
glViewport(0, 0, destination_surface->width, destination_surface->height);
const GLfloat vertex_transform[4 * 4] = {
2.0f / destination_surface->width, 0.0f, 0.0f, -1.0f,
0.0f, 2.0f / destination_surface->height, 0.0f, -1.0f,
0.0f, 0.0f, 0.0f, 0.0f,
0.0f, 0.0f, 0.0f, 1.0f,
};
// Switch to colour-key shader if we have to
glUseProgram(colour_key ? program_texture_colour_key.id : program_texture.id);
glUniform2f(colour_key ? program_texture_colour_key.uniforms.texture_coordinate_transform : program_texture.uniforms.texture_coordinate_transform, 1.0f / source_surface->width, 1.0f / source_surface->height);
glUniformMatrix4fv(colour_key ? program_texture_colour_key.uniforms.vertex_transform : program_texture.uniforms.vertex_transform, 1, GL_FALSE, vertex_transform);
glDisable(GL_BLEND);
@ -788,10 +812,10 @@ void RenderBackend_Blit(RenderBackend_Surface *source_surface, const RenderBacke
if (vertex_buffer_slot != NULL)
{
const GLfloat vertex_left = x * 2.0f / destination_surface->width - 1.0f;
const GLfloat vertex_top = y * 2.0f / destination_surface->height - 1.0f;
const GLfloat vertex_right = (x + (rect->right - rect->left)) * 2.0f / destination_surface->width - 1.0f;
const GLfloat vertex_bottom = (y + (rect->bottom - rect->top)) * 2.0f / destination_surface->height - 1.0f;
const GLfloat vertex_left = x;
const GLfloat vertex_top = y;
const GLfloat vertex_right = x + (rect->right - rect->left);
const GLfloat vertex_bottom = y + (rect->bottom - rect->top);
vertex_buffer_slot->vertices[0][0].position.x = vertex_left;
vertex_buffer_slot->vertices[0][0].position.y = vertex_top;
@ -963,9 +987,17 @@ void RenderBackend_PrepareToDrawGlyphs(RenderBackend_GlyphAtlas *atlas, RenderBa
last_green = green;
last_blue = blue;
const GLfloat vertex_transform[4 * 4] = {
2.0f / glyph_destination_surface->width, 0.0f, 0.0f, -1.0f,
0.0f, 2.0f / glyph_destination_surface->height, 0.0f, -1.0f,
0.0f, 0.0f, 1.0f, 0.0f,
0.0f, 0.0f, 0.0f, 1.0f,
};
glUseProgram(program_glyph.id);
glUniform2f(program_glyph.uniforms.texture_coordinate_transform, 1.0f / atlas->width, 1.0f / atlas->height);
glUniform4f(program_glyph.uniforms.colour, red / 255.0f, green / 255.0f, blue / 255.0f, 1.0f);
glUniformMatrix4fv(program_glyph.uniforms.vertex_transform, 1, GL_FALSE, vertex_transform);
// Point our framebuffer to the destination texture
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, glyph_destination_surface->texture_id, 0);
@ -987,10 +1019,10 @@ void RenderBackend_DrawGlyph(RenderBackend_GlyphAtlas *atlas, long x, long y, si
if (vertex_buffer_slot != NULL)
{
const GLfloat vertex_left = x * 2.0f / glyph_destination_surface->width - 1.0f;
const GLfloat vertex_top = y * 2.0f / glyph_destination_surface->height - 1.0f;
const GLfloat vertex_right = (x + glyph_width) * 2.0f / glyph_destination_surface->width - 1.0f;
const GLfloat vertex_bottom = (y + glyph_height) * 2.0f / glyph_destination_surface->height - 1.0f;
const GLfloat vertex_left = x;
const GLfloat vertex_top = y;
const GLfloat vertex_right = x + glyph_width;
const GLfloat vertex_bottom = y + glyph_height;
vertex_buffer_slot->vertices[0][0].position.x = vertex_left;
vertex_buffer_slot->vertices[0][0].position.y = vertex_top;